Determination of energy needs
The recommendation for energy intake in hospitalized animals has shifted within the last decade. Energy requirements for critically
ill animals are largely based on meeting calculated resting energy requirements (RER) and adjusting up or down as needed.
The previous use of illness factors (calculated RER multiplied by 1.2 to 1.5) added to the daily feeding recommendation of
hospitalized animals has fallen out of favor. In animals with voluntary food consumption, this is more a food-waste issue,
but with assisted enteral feeding intolerance to larger food volumes can lead to regurgitation, abdominal cramping, vomiting,
diarrhea and potential aspiration of vomitus or regurgitated material.
The two indirect formulas for calculating RER for dogs and cats are allometric (70* BWkg0.75) and linear ([30* BWkg] + 70).
The linear formula will overestimate RER for animals less than 2 kg, and as such the allometic formula is preferred for all
animals. Initial feeding should deliver 25 percent of the animal's RER over the first day and be increased gradually until
RER is reached in two to four days. Prior to each feeding, the tube should be aspirated with an empty syringe to monitor for
residual food volume, if applicable. Food should be warmed to room temperature and fed slowly to prevent vomiting. Warm water
should be used to flush the tube before and after feeding and after medication administration to prevent clogging. The animal's
temperature, respiratory rate, respiratory effort, lung sounds and development of a cough should be monitored closely for
any airway complications.
Some disease states may result in hypermetabolism and the amount of energy delivered will need to be increased to accommodate
increased losses, such as animals with protein-losing diseases, persistent diarrhea or diabetes mellitus. Like any medical
treatment, nutritional plans should be dynamic: Start with a goal to reach calculated RER and adjust the calories delivered
each day based on body-weight changes, physical-exam finding and known or expected ongoing losses.
Melissa Marshall, DVM, Dipl. ACVECC, received her veterinary degree from Tufts University in 1999. She completed a rotating
internship in small-animal medicine and surgery at Animal Specialty Group and her residency in emergency and critical care
at Angell Memorial Animal Hospital. She joined Red Bank Veterinary Hospital in 2005.
Lisa P. Weeth, DVM, Dipl. ACVN, received her veterinary degree from the University of California, Davis in 2002. She worked
in private practice for several years prior to returning to the University of California to complete a residency in clinical
nutrition. She joined Red Bank Veterinary Hospital in 2007.